For example, Japanese Patent Application Laid-Open Publication No. 2013-70297 (Patent Document 1) discloses a method of automatically setting LAG to a plurality of links which connect each interface relay and a plurality of fabric relays in a network relay system including the plurality of fabric relays and the plurality of interface relays. Japanese Patent Application Laid-Open Publication No. 2010-288168 (Patent Document 2) discloses a method in which each leaf switch transfers a packet received from a terminal to a specific route switch based on a destination address thereof and also transfers a learning packet to a specific route switch based on a source address thereof in a configuration including a plurality of leaf switches and a plurality of route switches relaying the communication therebetween.